package Utilities;

/**
 * @version
 *
 * @Date Apr 5, 2011
 * @author Rajeeb Saha
 *
 * http://lkamal.blogspot.com/2009/10/java-encrypt-decrypt-jce-salt.html
 *
 *        String password = "mypassword";
 *        String salt = "this is a simple clear salt";
 *        String passwordEnc = Protector.encrypt(password, salt);
 *        String passwordDec = Protector.decrypt(passwordEnc, salt);
 *
 *        System.out.println("Salt Text : " + salt);
 *        System.out.println("Plain Text : " + password);
 *        System.out.println("Encrypted : " + passwordEnc);
 *        System.out.println("Decrypted : " + passwordDec);
 */
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.*;

public class Protector {

    private static final String ALGORITHM = "AES";
    private static final int ITERATIONS = 2;
    private static final byte[] keyValue =
            new byte[]{'T', 'h', 'i', 's', 'I', 's', 'A', 'S', 'e', 'c', 'r',
        'e', 't', 'K', 'e', 'y'};

    public static String encrypt(String value, String salt) throws Exception {
        Key key = generateKey();
        Cipher c = Cipher.getInstance(ALGORITHM);
        c.init(Cipher.ENCRYPT_MODE, key);

        String valueToEnc = null;
        String eValue = value;
        for (int i = 0; i < ITERATIONS; i++) {
            valueToEnc = salt + eValue;
            byte[] encValue = c.doFinal(valueToEnc.getBytes());
            eValue = new BASE64Encoder().encode(encValue);
        }
        return eValue;
    }

    public static String decrypt(String value, String salt) throws Exception {
        Key key = generateKey();
        Cipher c = Cipher.getInstance(ALGORITHM);
        c.init(Cipher.DECRYPT_MODE, key);

        String dValue = null;
        String valueToDecrypt = value;
        for (int i = 0; i < ITERATIONS; i++) {
            byte[] decordedValue = new BASE64Decoder().decodeBuffer(
                    valueToDecrypt);
            byte[] decValue = c.doFinal(decordedValue);
            dValue = new String(decValue).substring(salt.length());
            valueToDecrypt = dValue;
        }
        return dValue;
    }

    private static Key generateKey() throws Exception {
        Key key = new SecretKeySpec(keyValue, ALGORITHM);
        // SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
        // key = keyFactory.generateSecret(new DESKeySpec(keyValue));
        return key;
    }
}
